There are seven isotypic forms of the microtubule protein β tubulin in mammals, but not all isotypes are synthesized in every cell type. In the adult organ of Corti, each of the five major cell types synthesizes a different subset of isotypes. Inner hair cells synthesize only βI and βII tubulin, while outer hair cells make βI and βIV tubulin. Only βII and βIV tubulin are found in inner and outer pillar cells, while βI, βII, and βIV tubulin are present in Deiters cells, and βI, βII and βIII tubulin are found in organ of Corti dendrites. During post-natal organ of Corti development in the gerbil, microtubules are elaborated in an orderly temporal sequence beginning with hair cells, followed by pillar cells and Deiters cells. Using β tubulin isotype-specific antibodies, we show that, in the gerbil cochlea, the same three isotypes are present in each cell type at birth, and that a cell type-specific reduction in the isotypes synthesized occurs in hair cells and pillar cells at an unusually late stage in development. No β tubulin isotypes were detected in mature afferent dendrites, but we show that this is because few microtubules are present in mature dendrites. In addition, we show that primary cilia in inner hair cells, a feature of early development, persist much later than previously reported. The findings represent the first description of developmental cell type-specific reductions in tubulin isotypes in any system.
|Original language||English (US)|
|Number of pages||13|
|Journal||Journal of Neurocytology|
|State||Published - Feb 2003|
ASJC Scopus subject areas
- Cell Biology